A recent BioSpace press release shares some exciting news for patients with non-small cell lung cancer, medullary thyroid cancer, and other thyroid cancers caused by RET gene mutations. Retevmo (selpercatinib) is the first drug therapy approved by the FDA specifically for the treatment of genetically-caused thyroid and lung cancers.
Types of Tumors Treated by Retevmo
Thyroid Cancer
Thyroid cancer is a type of cancer which begins in the thyroid, a gland in your throat. Your thyroid creates hormones which regulate weight, blood pressure, temperature, and heart rate. Thyroid cancer occurs when abnormal cells grow within the thyroid, creating tumors. It presents more often in women than in men. Some reports say that thyroid cancer is one of the fastest growing cancers within America.
There are multiple types of thyroid cancer. However, the three rarest forms are:
- Anaplastic: this rare, quick-spreading subset of thyroid cancer usually occurs in people older than 60. One hypothesis is that this form develops from existing thyroid cancer.
- Follicular: this form begins in the thyroid’s follicular cells, which help create hormones. This usually occurs in people older than 50. It generally does not spread to the lymph nodes, but can spread to other areas of the body.
- Medullary: this form is one of the types of thyroid cancer treated by Retevmo. It begins in the thyroid’s C cells, which produce the hormone calcitonin. Calcitonin is responsible for regulating calcium levels. Medullary cancer can spread to both the lymph nodes and other areas of the body.
Symptoms of thyroid cancer (medullary and other rare forms) include swollen lymph nodes, difficulty swallowing or breathing, a neck lump, swelling or pain in the neck and throat, a chronic cough, and vocal changes. Read more about thyroid cancer.
Non-Small Cell Lung Cancer
Non-small cell lung cancer (NSCLC) occurs when cancerous cells grow in lung tissue. However, the cancer cells differ for each type of non-small cell lung cancer. These include salivary gland carcinoma, adenocarcinoma, large cell carcinoma, and squamous cell carcinoma. Smoking is a large risk factor for the development of non-small cell lung cancer. Additional risk factors include a family history of lung cancer, HIV, air pollution, or exposure to radiation or other toxins.
Symptoms of NSCLC include wheezing, coughing up blood, extreme fatigue, unknown and uncontrolled weight loss, loss of appetite, chest pain, and a persistent cough that worsens over time. Learn more about non-small cell lung cancer from the National Cancer Institute.
Retevmo for Lung and Thyroid Cancer
Retevmo, developed by Eli Lilly, is a kinase inhibitor designed to treat:
- Non-small cell lung cancer in adults, particularly if it has spread;
- Advanced RET fusion-positive thyroid cancer in patients older than 12 which requires therapy that has not responded to radioactive iodine therapy, and
- Advanced medullary thyroid cancer (MTC) or medullary thyroid cancer which spread to another location in the body, for patients ages 12 or older who require treatment.
It was granted approval through the FDA’s Accelerated Approval program for the treatment of these three specific cancers. Retevmo also received Priority Review designation, Breakthrough Therapy designation, and Orphan Drug designation.
In other words, Retevmo is seen as a drug that treats a rare and serious condition, provides better improvement over other therapies for these conditions and allows the drug developer additional financial and business incentives to create the drug.
The lung and thyroid cancers treated by Retevmo resulted from a mutated or fused RET gene. RET stands for “rearranged during transfection.” According to the Genetics Home Reference, the RET gene is responsible for:
the normal development of several kinds of nerve cells, including nerves in the intestine and the portion of the nervous system that controls involuntary body functions such as heart rate…[and] normal kidney development and the production of sperm.
However, a mutated RET gene results in excessive cell growth. Retevmo blocks an enzyme called kinase to help restrict cancerous cell growth. Patients must be tested for the gene mutation before treatment.
Retevmo Clinical Trial
The therapy was approved following a clinical trial in which patients received 160mg of Retevmo 2x per day. They were looking to determine overall response rate (percentage of tumor reduction) and response duration. Results show:
- RET Fusion-Positive NSCLC
- The trial followed 105 patients who have been treated before with platinum chemotherapy. The overall response rate was 64%, meaning that 67 patients experienced tumor reduction or shrinkage to a specific level (indicated by the researchers). Overall, 81% of patients (approximately 85) had a response time of at least 6 months. This means that tumor reduction lasted for at least 6 months.
- The trial also examined 39 patients with no prior treatment. The overall response rate was 84% of patients (33), with 58% (23) having a 0-6 month response time.
- Medullary Thyroid Cancer
- This study followed 143 patients with RET-mutated medullary thyroid cancer. 55 patients were previously treated with chemotherapy, while 88 patients were not. The overall reduction rate for previously treated patients was 69% (38 patients) with 76% (42 patients) having at least a 6 month duration.
- For previously untreated patients, overall reduction rate was 73% (64 patients) with 61% (54 patients) having at least a 6 month response.
- RET Fusion-Positive Thyroid Cancer
- This study followed 19 patients who were radioactive iodine-refractory and had received prior treatment, and 8 patients with no prior treatments. For the first group, the overall response rate was 79% (15 patients), with 87% (17) experiencing a 6-month response. For the second group, the overall response rate was 100%, with 75% (6 patients) experiencing 6-month responses.
Adverse reactions included dry mouth, the heart taking longer to recharge between heartbeats, fatigue, low blood platelet and white blood cell count, liver damage, decreased levels of calcium and sodium, and heightened blood sugar, creatine, and AST and ALT liver enzymes.
